Former Environment Department assistant secretary Kevin Keeffe has told the royal commission he was concerned when the model was changed unexpectedly away from regulation and training towards a free market.

Mr Keeffe said he regarded as significant a change that required only supervisors to be trained, instead of all installers.

He said he was anxious about the implications and overall risk to young unskilled people undertaking the program without adequate training.

Yet Mr Keeffe conceded he did not voice his concerns about the changes in a brief days later to his then-minister Peter Garrett.

Mr Keeffe told the inquiry that given former senator Mark Arbib and officials from the Department of Prime Minister and Cabinet were driving the change, he was unlikely to challenge that.

He said the note was deferential, polite and trying not to buck the system.

Mr Keeffe also told the hearing key safety messages were not sent to installers until after the first death.

One of the four men who died, 25-year-old Matthew Fuller, was electrocuted in October 2009 installing insulation foil in a Logan home, south of Brisbane.

Five days later, the Federal Government issued its 11th installer advice notice, but was the first that stated only trained and competent installers should enter the roof space.

Richard Perry QC, acting for the Fuller family, asked how this could be done when the requirement for mandatory training had been removed in May.